Prognostic score for predicting respiratory admissions among patients with chronic obstructive pulmonary disease in primary care: development and validation in population cohorts (Birmingham Lung Improvement Studies (BLISS)).

OBJECTIVE: To predict the two year risk of respiratory admission to hospital among individuals with chronic obstructive pulmonary disease (COPD), with the development and validation (internal and external) of a prognostic score. DESIGN: Model development and validation in population cohorts. SETTING: Birmingham Lung Improvement Studies (BLISS) cohort of new and existing patients with COPD in primary care (model development and internal validation); Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) international cohort and UK primary care Clinical Practice Research Datalink (CPRD) Aurum database linked with Hospital Episode Statistics (external validation). PARTICIPANTS: 1894 patients with new and existing COPD from BLISS cohort; 1749 patients with moderate to very severe COPD from ECLIPSE cohort; 27 340 patients with COPD from CPRD Aurum database linked with Hospital Episode Statistics. MAIN OUTCOME MEASURES: One or more respiratory admissions within two years of cohort entry for development, internal validation, and external validation in CPRD; severe exacerbation within two years for external validation in ECLIPSE cohort. The model was developed from 23 candidate predictors by using multivariable logistic regression with bootstrapping for internal validation and adjustment for overfitting and optimism. Discrimination and calibration were assessed at each stage. Net benefit of the score (clinical utility) was examined across a range clinically relevant risk thresholds compared with use of individual score components. Subgroup and sensitivity analyses were conducted in the CPRD. The BLISS score was directly compared with the Bertens' score in the ECLIPSE cohort. Clinical implementation was explored with relevant stakeholders. RESULTS: Six predictors were retained (age, COPD Assessment Test score, respiratory admissions in the previous 12 months, body mass index, diabetes, forced expiratory volume in 1 second % predicted) to form the BLISS score for estimating an individual's ...